POSSIBLE ROLE OF THE SPLEEN IN THE DEVELOPMENT OF HYPERTENSION IN HUMANS

Abstract

Objective: Immune system (in particular T lymphocytes) is involved in the pathogenesis of arterial hypertension and microvascular remodelling. It has also been recently suggested a crucial role for spleen in the development and onset of hypertension, through a neuroimmune mechanism mediated by a splenic factor, the Placental growth factor (PIGF), in different models of experimental hypertension (Carnevale D, et al Immunity 2014, Carnevale D, et al. Nat Commun. 2016, Perrotta M, et al. Cardiovasc Res. 2018). However, to date no data are present in humans.Design and method: We investigated 29 patients: 19 were previously splenectomized for idiopathic thrombocytopenic purpura or marginal lymphoma (clinical conditions associated with good survival) and 10 patients underwent an elective surgical intervention (cholecystectomy) in the same period, well matched for ages, sex and cardiovascular risk factors. In all patients clinical and 24-hours blood pressure (BP) were recorded. Wall to lumen ratio of retinal arterioles (WLR) was obtained by Adaptive Optics as index of microvascular damage. Functional (basal) and structural (total) capillary density were studied by capillaroscopy before and after venous congestion. Results: The groups did not present statistically significant differences for clinical or 24-hours BP values (Clinical BP: 126.94 ± 8.20/72.38 ± 13.7 mmHg in splenectomized patients vs 125.56 ± 12.9/76.67 ± 5.59 mmHg in the cholecystectomized patients, p = NS; 24-hours BP: 119.7 ± 13.8/66.4 ± 6.60 vs 119.20 ± 8.76/69.10 ± 7.53 mmHg respectively, p = NS). No differences in central BP and Augmentation index were observed between the groups. Retinal arteriole morphology and capillary density did not differ between the groups. However, WLR was slightly higher, albeit not significant, in cholecystectomized than in splenectomized patients (Table). Conclusions: Our preliminary data did not confirm in humans the hypothesis of a difference in blood pressure values and indices of microvascular damage in splenectomized patients compared to cholecystectomized patients. However, a statistically not significant trend towards a greater WLR was observed in cholecystectomized patients. For a definitive conclusion about the involvement of the spleen in the genesis of hypertension also in humans it is necessary to extend the evaluation to a larger population.